Cranking time limiter



Dec. 9, 1941.

H. ELKiN ETAL CRANKING TIME LIMITER Filed Jan. 13, 1940 IN VENTOR.

manual/ 0 fibwv Patented Dec. 9, 1941 CRANKING TME LIMITER.

Manuel H. Elkln, Elmira Heights, and Frank T.

Christian, Elmira, N

assignors to Bendix Aviation Corporation, South Bend, Ind., acorporatlon of Delaware Application January 13, 1940, Serial No. 313,764

2 Claims.

The present invention relates to a cranking time limiter for enginestarter controls, and more particularly to a thermostatic controllingdevice for interrupting cranking after a predetermined time interval.

In certain types of engine installations equipped with automatic startercontrols, it is desirable to incorporate in the controlling means adevice for interrupting the cranking operation after a predeterminedtime if the engine fails to start for any reason. This is particularlytrue in cases where the power plant is normally unattended as inisolated installations for beacon lights and the like, and for certaintypes of air-conditioning units.

In order to conserve the charge of the starting battery as much aspossible, such cranking time limiter should become effective after atime interval sufllcient to secure a start under the normal range ofoperating conditions. Since this normal range may include widevariations in ambient temperatures, battery efllciency, enginestiffness, etc., the time control should be accurate irrespective ofsuch conditions in order to secure consistent operation.

It is an object of the present invention to provide a novel crankingtime limiter for internal combustion engines which is accurate anddependable in operation while being simple and economical inconstruction.

It is another object to provide such a device, the calibration of whichis substantially unafiected by usual variations in operating conditions.

It is a further object to provide such a device incorporating athermostatic controlling device which is positive in action while beingsusceptible of accurate calibration.

It is another object to provide such a device in which the thermostatoperates substantially without sliding friction such as might interferewith the accurate calibration thereof.

It is another object to provide such a device a ing the thermostaticcontrolling device with its associated elements.

In Fig. 1 of the drawing there is illustrated a starting circuit for aninternal combustion engine, not shown, including a. battery I connectedby a lead 2 to an automatic controlling device indicated generally bynumeral 3. This controlling device is of a well-known commercial formincluding a magnetic switch 4 which is connected by a lead 5 to astarting motor SM, the starting circuit being completed to the batterythrough the ground.

A control circuit for the magnetic starting switch 4 is providedincluding a manual switch 6 connected by lead 1 to battery lead 2 and bya lead 8 to a terminal 9 of thermostatic cranking time limiter indicatedgenerally by numeral ll. Terminal l2 of the cranking time limiter II isconnected to the engine ignition system and also through a lead I3 to abackfire circuit controller l4 which is of a commercial type forming nopart of the present invention. The circuit controller is connected by alead I! to the solenoid l6 of the magnetic starting switch 4. SolenoidI6 is connected by lead I! to a contact l8 which is normally inengagement with a contact IS on a pendulously mounted reed 2| which isgrounded at 22 to complete the control circuit.

Means for opening contacts IS, IS are provided including a coil 23 whichactuates a plunger 24 to move a pivoted lever 25 so that its free endengages the free end of the reed 2| and bends it back away from contactl8. Coil 23 is connected at one end by lead 26 to the starting motorlead 5 and is grounded at its other end as indicated at 21. Means forholding contacts l8, I9 open is provided in the form of a coil 28 alsogrounded at 21 and connected by a lead 29 to a vacuum operated switch 3|mounted on the intake manifold 32 of the engine and having contactsclosed by the vacuum in .the intake while the engine is running. Theswitch 3| is connected by lead 33 to terminal 34 of the thermostaticcranking time limiter l I.

As illustrated in Fig. 2, the cranking time limiter comprises a housing35 having a partition 38 fixed therein dividing it into an upper chamber31 and a lower chamber 38. A bracket 39 is fixedly mounted on thepartition 36, and a bimetallic plate 4i is rigidly fixed thereto at oneend as indicated at 42. A bimetallic arm 43 is fixed at one end to theplate 4| as indicated at 44. the two bimetallic parts being thermallyinsulated from each other as indicated at 45. The plate 4| is arrangedso'that a rise in temperature thereof will cause it to bend upward,while the arm as is reversely arranged so that when heated it bendsdownward. A heating coil 36 for the thermostatic arm as is grounded atone end thereon as shown atil and is connected by a lead it to a currentregulating device in the form of a ballast tube as mounted in the lowerchamber 36 or the housing 35. The ballast tube is connected by a lead 59to terminal 52 of the cranking time limiter which, as shown in Fig. l,is connected by a lead 53 to the starting motor lead 5.

A flexible yoke member 55 is mounted fixedly on the partition 3% whilebeing insulated therefrom as shown at 57. The yoke 56 is arranged toextend around the thermostatic arm 33, the anchorage 5? for the yokebeing located adjacent the bracket 39. The crosspiece 53 of the yokecarries a contact 59 which is normally in engagement with a fixedcontact ti connected by a lead 62 to the terminal 32' of the crankingtime limiter. Yoke 56 is connected by a lead 83 to the terminal 9 of thecranking time limiter.

Means for operating the yoke 56 to open contacts til, 65 by the actionof the thermostatic arm :33 is provided in the form of a compressionconnection between the end of the thermostatic arm and the crosspiece 58of the yoke. as here shown, this connection is in the form of acompression spring 66, the ends of which are seated in socket members t5and 65 which are formed to have rocking engagement with the end of thethermostatic arm 33 and the edge of the crosspiece 58 respectively. Itwill be readily under stood that since the spring 6% is under initialcompression, it forms in efiect a toggle connection with thethermostatic arm 53, and when said arm bends downward beyond thestraight-line position, the spring will move the crosspiece 58 upwardlyto open contacts 59, ti with a rapid snap action.

A contact ti! on an insulated bracket 68 is provided to act as a stopfor contact 5% and is connected by a lead iii to a terminal t9 which, asshown in Fig. l, is connected by a lead ii to an alarm device 52.

Terminals 9 and ii are connected by a resistor 33 of suitable value toreduce the current flowing through the coil 28 to a value just sumcientto reliably hold the plunger 26 in its attracted position so as tomaintain contacts i8, 59 open.

Means for adjusting the thermostatic arm 33 by flexing the bracket 39 isprovided in the form of an adjusting screw it tapped into the parti--tion 38. Manual means for returning the yoke 58 to normal position isprovided in the form of a plunger l5 slidably mounted in the side of thecasing 59 and a bracket it, and having a conical point ll adaptedtoengage the crosspiece 58 to move it to its lower position. A spring i8is preferably provided for normally maintaining the plunger it out ofthe path of movement of the crosspiece 58.

In operation, closure of the manual switch t completes a circuit fromthe battery 6 through leads V and 8 to terminal 55 of the cranking timelimiter. Since contacts 5t, ti are normally closed, current flowsthrough lead 63, yoke 5%, contacts bi, ti and lead 2 to terminal 62 fromwhence it flows through lead 63, circuit controller id and lead i 5 tothe solenoid it, and from thence through lead ii and contacts i3, i9 tothe ground at 22. Magnetic starting switch 5 is thereby closed,completing the starting circuit from battery l through leads 2 and 5 tothe starting motor to initiate the cranking operation. Closure of thestarting switch 4 causes energization of the coil 23 or the startercontrol 3, but attraction of the plunger 2% thereby is resisted by asingle turn coil it in the cranking circuit which prevents opening ofcontacts 98 and it during the cranking operation. If the engine startsproperly, the weakening of the starting circuit by the release of thecranking load from the starting motor perunits the coil '23 to overcomethe effect of the single turn coil l9. whereupon the plunger 24 isattracted to cause opening of contacts it, it, thus breaking the controlcircuitof the solenoid i6 and thereby permitting the starting switch 5to open. Thereafter contacts 58, it are held open by the energization ofcoil 28 which isenergized from the battery through leads l and 8,terminal 9, resistor 73, terminal 34, lead 33, vacuum switch 3i and lead29.

During the cranking operation, closure of starting switch 1 alsocompletes the heating circuit for the thermostatic arm 63, which circuitincludes battery lead 2, starting motor lead 5, lead 53, terminal 552,lead 51, ballast tube 59, lead 68, heating coil 65 and ground connectionii. The thermostatic arm #33 is thus caused to be heated during thecranking operation a rate held substantially constant by the ballasttube 19, and if the engine fails to start after a predetermined timeinterval. the thermostatic, arm bends downward suiiiciently to opencontacts t9, 6!, thus interrupting the control circuit for the magneticstarting switch it and causing the cranking operation to cease. At thesame time, contacts 59, 67 are closed. completing a circuit through leadiii, terminal it and lead ii to the alarm device 72.

Variations in the operation of the thermostat due to changes in ambienttemperatures are prevented by means of the thermostatic plate ii whichserves as a mount for the thermostatic arm 33 and which, as abovestated, is reversely arranged in respect thereto. In other words, a risein ambient temperature which causes the arm 33 to bend downward, willcause the plate ti to bend upward to a properly corresponding degree.Substantially uniform action of the thermostatic arm 63 is thus secured.

When an attendant summoned by the alarm device has removed theinoperative condition of the engine so as to make it possible to start,it is merely necessary for him to actuate the plunger it: to return thethermostatic contacts to normal position, whereupon the crankingoperation will be resumed in the usual manner.

Although but one embodiment of the invention has been shown anddescribed in detail, it will be understood that other embodiments arepossible and various changes may be made in the design and arrangementof the parts without departing from the spirit of the invention asdefined in the claims appended hereto.

What is claimed is:

1. In a cranking time limiter for internal combustion engines, a controlcircuit including a fixed contact, a flexible U-shaped yoke memberanchored atv its open end and carrying a contact on its closed endmovable by fiexure of the yoke member into and out of engagement withthe fixed contact, a thermostatic arm anchored at one end adjacent theanchorage of the yoke and extending into the yoke toward its free end, aspring interposed under pressure between the free ends of the arm andyoke to form a snapmember anchored to the housing adjacent the bracketin position to surround the thermostatic arm, a compression springbetween the end of the arm and the yoke, a fixed contact, a contact onthe yoke normally in engagement therewith, means for flexing the bracketto adjust the contacts, and means for heating the thermostatic armduring the cranking operation to cause opening of said contacts after apredetermined time therein, a thermostatic mounting plate fixed at 10 ofcranking.

one end on the bracket, an oppositely arranged thermostatic arm fixed tothe other end of the plate and insulated therefrom, a flexible yokeMANUEL H. ELKIN; FRANK T. CHRISTIAN.

